Armagh Observatory, 15th June 2023: Armagh Observatory reports that May 2023 was much warmer and drier than average, but slightly duller. Taking March, April, and May together the meteorological spring was the wettest at Armagh for 21 years, the warmest for 6 years, and the dullest for 4 years.
The average May temperature was 13.15 degrees Celsius (55.66 Fahrenheit), approximately 2.5 C warmer than the 225-year long-term (1796–2020) May average at Armagh (10.62 C) and 1.7 C warmer than the most recent (1991–2020) 30-year average (11.42 C). This was the warmest May at Armagh for six years, that is, since the only very
slightly warmer May 2017 (13.19 C), and the fifth warmest May on record at Armagh.
Although there were no exceptionally warm days, the average maximum temperature (18.0 C) was the fourth warmest at Armagh, shared with May 1859, since daily temperature measurements began at the Observatory around 1795. Similarly, the average minimum temperature (8.3 C) was the fourth warmest minimum May temperature on record at Armagh, shared with May 2014. These results occurred because 26 of the month’s 31 days achieved maximum temperatures greater than the most recent (1991–2020) 30-year average maximum for May (15.8 C) and 22 had minimum temperatures higher than the most recent 30-year average minimum (7.0 C), leading to the monthly mean of 13.15 C.
The warmest day (highest maximum temperature) was an unremarkable 23.3 C on the 30th followed by 22.9 C on the 31st. These two days started a long and unusually warm, dry spell extending well into the first half of June. The 30th of May was the warmest day of the year up to the end of the month, but this was soon surpassed by the still warmer days
of early June, for example the 4th and 5th (maximum temperatures 24.2 C and 24.8 C) and the 10th (maximum temperature 25.8 C). The coolest days this May, that is, those days with the lowest maximum temperatures, were 13.4 C on the 12th, followed by 13.5 C on the 30th and 14.1 C on the 31st.
The highest minimum temperature, notionally the warmest night, was 12.8 C on the 8th, followed by 11.5 C on the 21st and 11.2 C on the 20th. The lowest minimum, or coldest night, was 3.9 C on the 15th followed by 4.2 C on the 29th and 5.3 C on the 16th. There were 6 nights with ground frost, that is, nights when the grass temperature fell to less than or equal to zero Celsius, the coldest three of which were -1.8 C on the 30th, -1.6 C on the 15th, and -1.4 C on the 16th. There were no air frosts.
Total May precipitation was 33.35 mm (1.31 inches) including 5 trace values (that is, 33.1 mm if trace values are ignored). This is approximately 57% of both the 183-year (1838–2020) long-term average May precipitation at Armagh (58.6 mm) and the most recent (1991–2020) 30-year average (58.2 mm). The wettest day was the 20th with 7.8 mm (0.31 inches) of rainfall, followed by the 9th with 5.0 mm.
This year the first swallows and swifts were seen over the Observatory on the 4th and 8th of May respectively. There were no gales, hail or thunder, but rainbows were seen on the evening of the 10th. There were 170.0 hours of strong sunshine, which is close to the average for May at Armagh, namely 176.4 hours for the 140-year (1881–2020) long-term average and 173.8 hours for the most recent (1991–2020) 30-year average. The sunniest day was the 30th with 14.4 hours of strong sunshine, followed by 12.4 hours on the 29th and 12.2 hours on the 31st.
Taking the three months March, April and May together the meteorological spring was the wettest at Armagh for 21 years, the warmest for 6 years and the dullest for 4 years. The mean spring temperature was a very warm 9.9 C, approximately 1.8 C warmer than the 225-year (1796–2020) long-term spring average at Armagh (8.1 C) and 0.9 C warmer than the most recent (1991–2020) 30-year average (9.0 C). Spring 2023 was the warmest spring at Armagh for 6 years, that is, since the exceptionally warm spring of 2017 (10.2 C), and the fourth warmest spring on record at Armagh (shared with spring 2007, 1893 and 2022).
Total spring precipitation was 235.55 mm including 13 trace values. Despite the dry May, the very wet March and wetter than average April combined to make this spring the wettest at Armagh for 21 years, that is, since spring 2002 (278.0 mm). This spring was approximately 41% wetter than the 183-year (1838–2020) long-term spring average at Armagh (167.0 mm) and 35% more than the most recent (1991–2020) 30-year average (173.8 mm).
With each of the three spring months being slightly duller than average, the total of 392.5 hours of strong sunshine was approximately 92% of the 140-year (1881–2020) long-term spring average at Armagh (424.4 hours) and 91% of the most recent (1991–2020) 30-year average (431.6 hours). This was the dullest spring at Armagh for four years, that is, since
the exceptionally dull spring 2019 (312.7 hours).
These data refer to observations at Armagh Observatory, which has been recording the weather at Armagh since 1795.
FOR FURTHER INFORMATION PLEASE CONTACT: Mark Bailey at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; mark.bailey@armagh.ac.uk; URL: http://climate.armagh.ac.uk/
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